New testcase for PR362: Icky code generated for std::min/std::max

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16408 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/CPP_min_max.llx

@@ -0,0 +1,34 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep select | not grep 'int\*'
+
+; This testcase corresponds to PR362, which notices that this horrible code
+; is generated by the C++ front-end and LLVM optimizers, which has lots of
+; loads and other stuff that are unneeded.
+;
+; Instcombine should propagate the load through the select instructions to
+; allow elimination of the extra stuff by the mem2reg pass.
+
+implementation   ; Functions:
+
+void %_Z5test1RiS_(int* %x, int* %y) {
+entry:
+	%tmp.1.i = load int* %y		; <int> [#uses=1]
+	%tmp.3.i = load int* %x		; <int> [#uses=1]
+	%tmp.4.i = setlt int %tmp.1.i, %tmp.3.i		; <bool> [#uses=1]
+	%retval.i = select bool %tmp.4.i, int* %y, int* %x		; <int*> [#uses=1]
+	%tmp.4 = load int* %retval.i		; <int> [#uses=1]
+	store int %tmp.4, int* %x
+	ret void
+}
+
+void %_Z5test2RiS_(int* %x, int* %y) {
+entry:
+	%tmp.0 = alloca int		; <int*> [#uses=2]
+	%tmp.2 = load int* %x		; <int> [#uses=2]
+	store int %tmp.2, int* %tmp.0
+	%tmp.3.i = load int* %y		; <int> [#uses=1]
+	%tmp.4.i = setlt int %tmp.2, %tmp.3.i		; <bool> [#uses=1]
+	%retval.i = select bool %tmp.4.i, int* %y, int* %tmp.0		; <int*> [#uses=1]
+	%tmp.6 = load int* %retval.i		; <int> [#uses=1]
+	store int %tmp.6, int* %y
+	ret void
+}